1. Field of the Invention
The present invention relates to a magnetic head unit to write and/or read signal to and/or from a disc-shaped recording medium, and a recording and/or reproducing apparatus comprising the magnetic head unit.
2. Description of Related Art
The recording and/or reproducing apparatuses for recording and/or reproducing signal to and/or from a signal recording surface of a disc-shaped recording medium such as a flexible disc, are widely used in personal computers as well as in office computers, word processors. The recording and/or reproducing apparatuses have been showing a remarkable prevalence.
The recording and/or reproducing apparatus comprises a magnetic head unit which writes and/or reads signal to and/or from a disc-shaped recording medium set in the apparatus.
The magnetic head unit comprises a pair of support arms and a pair of magnetic heads each including a magnetic head element and attached to each of the support arms to oppose each other. A disc-shaped recording medium is placed between the pair of magnetic heads to write and/or read signal with respect to a signal recording surface of the disc-shaped recording medium via the magnetic head elements.
Referring now to FIG. 1, there is illustrated a conventional magnetic head unit. This magnetic head unit is generally indicated with a reference 100. As shown in the form of a partial section view in FIG. 1, the magnetic head unit 100 comprises a pair of support arms 101 supported at base portions thereof, a pair of gimbal plates 102 each mounted at free end of each of the support arms 101, and a pair of magnetic heads 103 opposite to each other and each disposed on each of the gimbal plates 102. There is provided a pair of pivots 104 each formed integrally with each of the pair of support arms 101. The magnetic head unit 100 is adapted such that each of the pair of magnetic head 103 is moved by toward a disc-shaped recording medium 105 by each of the pivots 104 via the gimbal plate 102, whereby the magnetic heads 103 are moved to follow up with a displacement or deflection of the disc-shaped recording medium 105 to assure a stable write and read.
The disc-shaped recording medium 105 the recording and/or reproducing apparatus constructed as in the above writes and/or reads, is usually encased in a cartridge 106 for the purpose of protecting the signal recording surface thereof when it is set in the recording and/or reproducing apparatus.
The cartridge 106 has formed therein an opening 107 through which the magnetic head is introduced. When the magnetic head unit 100 is used to write and/or read the disc-shaped recording medium 105, the magnetic heads 103 of the magnetic head unit 100 is introduced into the cartridge 106 through the opening 107, and the magnetic head elements of the magnetic head 103 write and/or read signal to and/or from the disc-shaped recording medium 105 while sliding over the signal recording surface of the disc-shaped recording medium 105 inside the cartridge 106.
Therefore, in the magnetic head unit 100, the thickness t1 of the magnetic heads 103 is larger than the distance t2 from the surface of the cartridge 106 to the disc-shaped recording medium 105 so that when the magnetic heads 103 go into the cartridge 106, the support arms 101 will not touch the cartridge 106.
Recently, a flexible disc has been proposed which has a larger recording capacity than the flexible discs currently used in practice. This large capacity flexible disc has same outside dimensions as the conventional flexible discs. However, it has a storage capacity of tens to hundreds MB while the conventional flexible discs have a storage capacity of 1 to 2 MB.
In these situations, it has been proposed from the standpoint of a versatility to use a recording and/or reproducing apparatus destined to write and/or read such large capacity flexible discs as well as the conventional flexible discs. Namely, the lower capacity flexible discs are also usable with the proposed recording and/or reproducing apparatus.
As shown in FIG. 2, such a recording and/or reproducing apparatus has a magnetic head unit using a pair of magnetic heads 103 each comprising a magnetic head element 111 for the large capacity flexible discs (will be referred to as "high density medium-oriented magnetic head element" hereinafter for the convenience of the explanation) and a magnetic head element 112 for the conventional flexible discs (will be referred to as "low density medium-oriented magnetic head element" hereinunder for the same reason). Also, each of the magnetic heads 103 has formed in an intermediate portion thereof in the direction of the head thickness a concavity 113 open to the lateral side of the magnetic head 103 and in which a coil is wound on the high density medium-oriented magnetic head element 111.
In this recording and/or reproducing apparatus, a large capacity flexible disc is set in place in the apparatus is spun at a speed of about 3,600 rpm, for example, and the high-capacity magnetic head element 111 is used to write or read signal to or from the flexible disc. On the other hand, when a conventional flexible disc set in place in the apparatus is spun at a speed of 300 rpm, for example, the signal is written to and read from, the flexible disc by the low density medium-oriented magnetic head element 112.
In the mean time, the aforementioned magnetic head unit 100 is so constructed to allow the magnetic head 103 to follow up with the moving disc-shaped recording medium 105 for a stable write and read, the magnetic heads 103 are forced towards the disc-shaped recording medium 105 by the pivots 104 formed integrally with the pair of support arms 101 via the gimbal plates 102.
In this magnetic head unit 100, however, since the thickness t1 of the magnetic head 103 is set larger than the distance t2 between the surface of the cartridge 106 and disc-shaped recording medium 105 as mentioned above, the point at which the pivot 104 forces the magnetic head 103 via the gimbal plate 102 is off the surface of the magnetic head 103 sliding on the disc-shaped recording medium 105.
Thus, along with the spinning of the disc-shaped recording medium 105 and seeking operation of the magnetic head unit 100, the magnetic head 103 is applied with a force under which the magnetic head 103 is inclined, so that the posture of the magnetic head 103 in relation to the disc-shaped recording medium 105 cannot be kept stably.
Especially when a large capacity flexible disc is used with the recording and/or reproducing apparatus, since the flexible disc is spun at a speed of about 3,600 rpm, so a large force is applied to the magnetic head 103 as the flexible disc is spun, and thus it is difficult to keep the magnetic head 103 stably in position in relation to the flexible disc.
Therefore, in order to stabilize the posture of the magnetic head 103, the magnetic head 103 should desirably be designed to have a reduced thickness so that the point at which the pivot 104 forces the magnetic head 103 towards the disc-shaped recording medium 105 by means of the gimbal plate 102 is nearer to the surface of the magnetic head 103 sliding on the disc-like recording medium 105.
In the magnetic head unit 100 of a recording and/or reproducing apparatus adapted to make write or read with respect to a large capacity flexible disc, however, if the magnetic head 103 has an excessively small thickness, the above-mentioned coil winding concavity 113 cannot be formed in an intermediate portion of the magnetic head 103 in the direction of the head thickness.